Alternative scenarios of relativistic heavy-ion collisions. II. Particle production

Particle production in relativistic collisions of heavy nuclei is analyzed in a wide range of incident energies 2.7 GeV ≤√sNN≤ 62.4 GeV. The analysis is performed within the three-fluid model employing three different equations of state (EoSs): a purely hadronic EoS, an EoS with the first-order phase transition, and an EoS with a smooth crossover transition. It is found that the hadronic scenario fails to reproduce experimental yields of antibaryons (strange and nonstrange), starting already from lower Super Proton Synchrotron (SPS) energies, i.e., √sNN> 5 GeV. Moreover, at energies above the top SPS one, i.e., √sNN> 17.4 GeV, the midrapidity densities predicted by the hadronic scenario considerably exceed the available Relativistic Heavy-Ion Collider data on all species. At the same time the deconfinement-transition scenarios reasonably agree (to a various extent) with all the data. The present analysis demonstrates certain advantage of the deconfinement-transition EoSs. However, all scenarios fail to reproduce the strangeness enhancement in the incident energy range near 30A GeV (i.e., a horn anomaly in the K⁺/π⁺ ratio) and yields of φ mesons at 20A--40A GeV.